Quantum Standard Clocks in the Primordial Trispectrum

TL;DR

This paper computes the primordial trispectrum in quasi-single field inflation, revealing oscillatory signals in soft limits that serve as quantum primordial standard clocks, using a simplified mixed propagator approach.

Contribution

It introduces a novel calculation of the trispectrum with general sound speeds and highlights the quantum standard clock signals in soft limits, advancing understanding of primordial non-Gaussianities.

Findings

Identification of oscillatory patterns in the trispectrum's shape function.

Application of the mixed propagator method simplifies complex calculations.

Enhanced understanding of soft limit behaviors in primordial non-Gaussianities.

Abstract

We calculate the primordial trispectrum of curvature perturbation in quasi-single field inflation, with general sound speeds for both the inflaton and the massive scalar. Special attention is paid to various soft limits of the trispectrum, where the shape function shows characteristic oscillatory pattern (known as the quantum primordial standard clock signal) as a function of the momentum ratio. Our calculation is greatly simplified by using the "mixed propagator" developed under a diagrammatic representation of the in-in formalism.